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Mosfets for Tubelab SE?

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Tubelab_com

Tubelab_com

Member
Joined 2005
tubelab.com
Are the 500V Cornell Dubilier 380LX any good for the Simple SE?
I bought some and stuffed them in an SSE board. They seem to work OK but I haven't used the amp enough to judge reliability. I would guess that they will be OK if you mount the caps on the back of the board to avoid radiant heat from the output tubes.

Newark (Farnell) now has some 105C rated Nichicons. I just got 10 of them but haven't tested them yet.
 
boywonder

boywonder

Member
Joined 2008
What he said........

If I had to re-phrase the question today....

If the mosfet drain-source voltage rating is 500V, what prevents that spec from being exceeded (especially at startup) in the circuit? It seems that with 300B's the source voltage is as negative as -300 volts or more, not considering the + voltage on the drain.

Still wondering myself.........
 
C

Captn Dave

Member
Joined 2008
cddeluca said:
Found this device:
FQH8N100C Fairchild Semiconductor MOSFET

It's a 1000V, N-channel with a Crss of essentially zero above a Vds of 10V. Seems ideal?
Click to expand...

I too am looking for a suitable MOSFET. I see this post is quite old. Did you use this MOSFET?

It looks like a pretty good choice as the Crss is low and flat, however I'm not real comfortable with the "essentially zero above 10v" Are you looking at the capacitance graph? That scale is 250 volts per minor division It's really hard to say other than it's probably less than 25pf. This scale seems to be typical and is not very helpful. I note in the electrical characteristics Crss is listed as 16 typical. That's not bad but not as good as the 2SK2700.

The infineon IPA90R1K0C3 is interesting. Very low Crss between 2 and 5 pf on a more useful log scale. 31 watts power dissipation, 900 v.

So, I'm wondering how must power the MOSFET needs to handle? The 2SK2700 was rated it 400W IIRC. The Crss seems to increase with larger powered devices. How much is enough FOR THE 845 application?
 
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michaeljessen

michaeljessen

Member
Joined 2017
I am looking for a substitute for the Mosfet 2SK3563Q-ND Can I use FDPF5N50NZ-ND in sted ? Is it a usefulness substitute?

I had a chat with an Engineer from Digikey. He Came up with two sub. TK6A60DSTA4QM-ND and FDPF5N50NZ-ND There are apposing zener diodes across the gate and source just like the 2SK3563Q-ND. Witch of these are the best substitute for 2SK3563Q-ND ?

I do not have the Knowledge to see it on the data sheets. Can somebody help?

I get a link to chip1stop.com they have 400 2SK3563Q in stock. I buy a pair because I dit not know enough about a substitute for 2SK3563Q-ND This will possible be sold out quick I think.

2SK3563(Q) Toshiba | Transistor | MOSFET - chip1stop.com
 
Tubelab_com

Tubelab_com

Member
Joined 2005
tubelab.com
See if you can get any NDF04N60ZG. I know that Mouser still has about 1000. I just ordered some and they are on their way. I have been using them in my amps with good results, but they are now on the endangered species list as well. It seem that HV mosfets have a product lifetime measured in months. If they don't find their way into a high volume product, they go away.

There have been too many builders, especially in Europe who have been burned by counterfeit Mosfets and CCS chips from Ebay.

Mouser number for the On Semi mosfets:

863-NDF04N60ZG-001

Digikey has zero left
 
K

kcom00

Member
Joined 2012
Toshiba lists the TK5A50D as a replacement for 2SK3563.
As far as I can see the specs are very close.
Anyone has any concerns with this sub?

We've already gone through a few options for the Mosfets; 2SK2700, NDF02N60ZH, 2SK3564, NDF04N60ZG, maybe TK5A50D is the next available part?
 
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